How to Determine the Quality of an Integrated Circuit

The quality of an integrated circuit (IC) can be assessed by measuring parameters such as pin resistance, pin voltage, and pin waveforms. Pin resistance is one of the key indicators for detecting whether an IC is damaged. The pin resistance of an IC can be classified into in-circuit resistance and out-of-circuit resistance.

• In-circuit resistance refers to the measured value when the IC is connected to peripheral components (also called external elements) on a printed circuit board (PCB). Since the IC and its peripheral components have specific matching resistance values on the PCB, comparing the in-circuit resistance with standard reference values can help determine whether the IC is faulty.

• Out-of-circuit resistance refers to the resistance measurement of a bare IC chip that is not installed in an application circuit.

The drawback of out-of-circuit resistance testing is that the IC must be desoldered from the PCB to measure the resistance between pins or between pins and the ground pin. The measured out-of-circuit resistance must also be compared with standard values. If there is a significant deviation, further analysis is required before making a judgment. Typically, an analog multimeter is used to measure IC pin resistance. For linear pins, readings from different multimeters are usually consistent, whereas for nonlinear pins, measurements may vary significantly across different multimeters.

Pin voltage measurement is another key parameter for detecting IC faults. The pin voltage of an IC is a DC value, which can be categorized into different states, such as signal-present voltage and signal-absent voltage.

• Different ICs in different products may or may not have the same pin voltage values, but it is impossible for all pin voltages to be identical.

• Even for the same IC model in different products, pin voltages may vary. However, if the test equipment, measurement range, and application circuit conditions are the same or similar, the measured voltage values should not differ significantly.

• Additionally, when measuring voltage, it is important to note the unit of measurement for IC pin voltages.

Pin waveforms represent the instantaneous values of an IC during operation in an application circuit.